1. Technical Field of the Invention
This invention relates to telecommunication systems and, more particularly, to a system and method of sending data packets over a radio interface using multiple data transmission paths.
2. Description of Related Art
It has been demonstrated that most Internet Protocol (IP)-based applications in Terminal Entities (TEs) that are running real-time applications such as Voice-over-IP (VoIP), Streaming Video, or even best effort applications involving large graphical file downloads are severely challenging the limited resources offered by 2G and 3G wireless packet networks. Moreover, most of the bandwidth and delay limitations occur in the radio interface portion of the transmission path. Because of the bandwidth and delay limitations of the packet radio interface, TEs today are unable to open up more than one bandwidth-intensive application at a time.
Presently, Universal Mobile Telecommunications System/Wideband Code Division Multiple Access (UMTS/Wideband CDMA) standards allow up to four different Quality of Service (QoS)-based Packet Data Protocol (PDP) Contexts to be opened for any single PDP address (IP address). The four QoS classes represent application requirements such as Real Time, Best Effort, and so on. These are used to set up radio interface and core network scheduling along with traffic shaping. However, even with QoS-based scheduling and differential handling of different application requests, only a single data path exists for all packets traversing the network. Additionally, it has been shown that VoIP protocols add sizable overheads in addition to the actual speech frame, and therefore their transmission becomes very inefficient over packet radio interfaces.
Most VoIP schemes today rely on heavy compression algorithms that operate by changing the header state, and are therefore not designed for the lossy environment prevalent on the radio interface. Once packet loss is factored in, medium quality VoIP over the packet radio interface becomes extremely difficult, if not impossible, to achieve.
Therefore, it would be advantageous to have a system and method of sending data packets over a packet radio interface that relieves the bandwidth and delay limitations currently experienced, and enables TEs to run more than one bandwidth-intensive application at a time. The present invention provides such a system and method.
In one aspect, the present invention is a method in a packet-switched radio access network of sending data packets over a radio interface from a Mobile Station (MS) to a Radio Network Controller (RNC) using multiple data transmission paths. The method includes the steps of providing the MS with a first data transmission path through a first base station (BS1) and, when the MS launches a new real-time application, sending a new registration message from the MS to a server such as a Serving GPRS Service Node (SGSN) that performs radio access bearer control. It is then determined within the network, whether the bandwidth required by the new application exceeds the bandwidth capacity of the radio interface portion of the first data transmission path. If so, the method identifies a second BS (BS2) that has the capacity to provide a portion of the radio interface bandwidth required. This is followed by providing the MS with a second data transmission path through BS2; inserting by the MS, an identifier label on each upstream data packet; and transmitting a portion of the labeled upstream data packets to BS1 and a portion to BS2 as separate data streams over the radio interface. The separate upstream data portions are then sent from BS1 and BS2 to the RNC where they are combined using the identifier labels.
The method may also include the steps of sending downstream data packets for the MS from the SGSN to the RNC; inserting by the RNC, an identifier label on each downstream data packet; and transmitting a portion of the labeled downstream data packets to BS1 and a portion to BS2 as separate data streams over the radio interface. The separate downstream data portions are then sent from BS1 and BS2 to the MS where they are combined using the identifier labels.
In another aspect, the present invention is a system in a packet-switched radio access network for sending data packets over a radio interface from an MS to a plurality of BSs and an RNC using multiple data transmission paths. The MS has a first radio interface data transmission path established to a first base station (BS1). The system includes a bearer-control server for providing radio access bearer control in a service area, and for notifying the RNC when the MS launches a new real-time application. The system also includes means within the MS for inserting an identifier label on each upstream data packet and dividing an upstream data stream into a plurality of upstream portions, each upstream portion being transmitted by the MS to a different BS based on a BS-identifier and a code. An RNC is connected to the bearer-control server, and controls the plurality of BSs. The RNC includes a bandwidth analyzer for determining whether the bandwidth required by the new application exceeds the bandwidth capacity of the first radio interface data transmission path; and means for identifying a second BS (BS2) that has the capacity to provide a portion of the radio interface bandwidth required. A first signaling mechanism receives a plurality of upstream data portions from the plurality of BSs. The RNC also includes a combiner that combines the plurality of upstream data portions into a combined upstream data stream based on the identifier labels; and a second signaling mechanism for sending the combined upstream data stream to the bearer-control server.
In yet another aspect, the present invention is an RNC in a radio access network that enables an MS that is running a first application over a first radio interface data transmission path through a first base station (BS1) to launch a second application at the same time. The RNC includes a bandwidth analyzer for determining whether the bandwidth required by the second application exceeds the bandwidth capacity of the first radio interface data transmission path; and means for identifying a second base station (BS2) that has the capacity to provide a portion of the radio interface bandwidth required. The RNC also includes means for instructing the MS to insert identifier labels in each upstream data packet, to divide its upstream data stream into two upstream data portions, and to transmit a first portion from the MS to BS1 and a second portion from the MS to BS2. The RNC also includes a first signaling mechanism for receiving the first portion from BS1 and the second portion from BS2; a combiner that combines the first and second upstream data portions into a combined upstream data stream based on the identifier labels; and a second signaling mechanism for sending the combined upstream data stream to a bearer-control server.